How to embed nested forms in Symfony

How to embed nested forms in Symfony with no related entities

Sometimes you may need to embed forms in Symfony with no related entities, no OneToMany or other relation, you can just add a form inside another as you would do with a new field. The reason to do this could be to group the two forms inside a single action to submit all data in one click, for example. These two entities are not mapped to each other, they are just there for the sake of a grouped action.

// Parent form
public function buildForm(FormBuilderInterface $builder, array $options)
	// Add nested form
	$builder->add('article', new ArticleNestedType(
		$this->em // Pass parameters to nested form if any
        array('data' => new Article())); // Pass options parameters to nested form

In controller, handle data base actions when form is submitted:

if ($form->isValid()) {
    // Persist new Entity
    if (true === isset($form->getData()['article'])) {
        $article = $form->getData()['article'];
        $em = $this->getDoctrine()->getManager();

Then in twig to display child form:

{{ form_widget(form.article) }}